Former UFC champion Frank Mir and former Strikeforce champion Alistair Overeem square off in a feature bout at UFC 167 – the promotion’s 20th Anniversary event – but it could be the last time we see the loser in the Octagon.

UFC president Dana White met with reporters at a media day scrum in Toronto on Thursday. When he was asked if it was a do-or-die situation for Mir and Overeem, he didn’t mince words.

White responded, “Definitely.”

It would be an odd thing to see the UFC’s heavyweight roster without Mir’s name listed.

Mir has been fighting in the Octagon since 2001, debuting for the UFC in the third fight of his professional career.

He has held the UFC heavyweight championship and the interim version of it. He has more fights, wins, and finishes than any other heavyweight in the promotion’s history.

Mir has racked up an overall record of 16-8, but enters the fight with Overeem having lost three consecutive bouts to Junior dos Santos, Daniel Cormier, and Josh Barnett.

Overeem (36-13, 1 NC) is one of the most decorated heavyweight champions in combat sports not to hold the UFC belt. He is a Strikeforce and Dream champion in mixed martial arts, and is a K-1 World Grand Prix champion in kickboxing.

He entered the Octagon having won 10 of his 11 most recent fights, which included a no-contest decision in a fight with Mirko “Cro Cop” Filipovic. But, Overeem has only won a single fight since making the jump from Strikeforce to the Octagon, where he has fought three times.

Overeem enters the fight with Mir off of back-to-back knockout losses to Antonio “Bigfoot” Silva and Travis Browne.

His tenure has also been mired in controversy due to failing a surprise out-of-competition drug test in Nevada, which derailed his shot at the heavyweight championship.